248 EAST A FRICAN M E DICAL JOURNAL May 2008 East African Medical Journal Vol. 85 No. 5 May 2008 UNUSUAL PRESENTATION OF iDIOPATHIC RETROPERITONEAL FIBROSIS: CASE REPORT N. Twahirwa, MBChB, Radiology Resident and J. Rees, MBChB (Edin), FRCR, FRCP, Professor and Director, PGME, Department of radiology, aga Khan university hospital, nairobi, P.O. Box 30270-00100, nairobi, Kenya Request for reprints to: Dr. N. Twahirwa, Aga Khan University Hospital, Nairobi, P.O. Box 30270-00100, Nairobi, Kenya UNUSUAL PRESENTATION OF IDIOPATHIC RETROPERITONEAL FIBROSIS: CASE REPORT N. tWAHIRWA and J. rEES SUMMARY Idiopathic retroperitoneal fibrosis (IRF) is an uncommon entity described as progressive proliferation of connective tissues leading to a fibrous plaque-like lesions that encases the aorta and inferior vena cava inferior to the level of the renal arteries. Mass forming retroperitoneal fibrosis is rare. We present a rare case of a unilateral focal retroperitoneal mass simulating a tumour encasing the middle third of the left ureter, with involvement of the ipsilateral scrotum. INTRODUCTION focal retroperitoneal mass encasing the middle third of the ureter and extending inferiorly along the Idiopathic retroperitoneal fibrosis (IRF) is an psoas muscle (measuring crania-caudal 14.2 cm, uncommon entity described as progressive anteroposterior 3.4 cm and transverse 5.6 cm) with proliferation of connective tissues leading to a fibrous proximal hydroureter and perinephric stranding. plaque-like lesions that encase the aorta and inferior The peritoneum was otherwise clear and no calculus vena cava inferior to the level of the renal arteries. was seen. Mass forming retroperitoneal fibrosis is rare. On standard CT abdominal examination (Figures 3 and 4) the mass showed enhancement CASE REPORT equivalent to the adjacent psoas muscle. The left perinephric stranding and hydroureter seen are due A 37 year old male presented at Aga Khan University to the obstructive effect of the mass. A differential Hospital accident and emergency department in July diagnoses included lymphoma, retroperitoneal 2007 with a two-week history of intermittent sharp left fibrosis and sarcoma. flank pain with no radiation or aggravating/relieving factors. He denied any episode of fever, dysuria, Biopsy and histology: The patient underwent Ct frequency, urgency or haematuria. There was no guided biopsy and histological examination known allergy or chronic medication history. A right (Figure 5) confirmed the features consistent with inguinal lymphnode was excised at nine years, which retroperitoneal fibrosis. On clinical review he was was benign on histology. Examination revealed tender found to have a left hydrocele that was confirmed and rigid left flank muscles. Urolithiasis was queried on ultrasound. Both testes were normal (Figures 6 and CT KUB requested. and 7). The patient thereafter had double J stenting and Jabouleys procedure for the ureteral obstruction CT KUB and abdomen: Unenhanced CT KUB (Figures and hydrocele respectively. Post operatively he was 1 and 2) demonstrated a left iso-attenuating unilateral started on tamoxifen 20mg BD. May 2008 EAST A FRICAN M E DICAL JOURNAL 249 Figures 1 and 2 Axial sections of CT KUB demonstrating left retroperitoneal iso-attenuating mass abutting the ipsilateral psoas muscle with associated hydroureter and perinephric stranding Figures 3 and 4 Axial and coronal enhanced CT abdomen re-demonstrated left periureteral mass that has enhancement equivalent to the adjacent psoas muscle 250 EAST A FRICAN M E DICAL JOURNAL May 2008 Figure 5 Histology micrograph shows dense fibrous and fatty connective tissue infiltrated by a mixed inflammatory cell infiltrate comprising of occasional neutrophils, eosinophils and a predominace of lymphocytes with dispersed plasma cells and histiocytes Figures 6 and 7 Bilateral testicular ultrasound, demonstrating left sided hydrocele and normal testicular parenchymal DISCUSSION kidneys as well as lymphoma and sarcoma (2). Systemic fibrosing diseases that have been associated with Retroperitoneal fibrosis is a rare disease entity with retroperitoneal fibrosis include fibrous pseudotumour an estimated incidence of 1:200 000 population. of the orbit, Riedel’s thyroiditis, sclerosing cholangitis Albarran reported the first documented case in and mediastinal fibrosis (3). 1905, and Ormond established the disease entity Tuberculosis has also been associated with in 1948(1), explaining why it’s also known as retroperitoneal fibrosis (2). Pathologically, IRf “Ormond’s syndrome”. manifests as progressive inflammation and fibrous Two thirds of retroperitoneal fibrosis cases are proliferation of connective tissue over the anterior idiopathic. The remainder are due to an autoimmune surface of the lower lumbar vertebrae, below the reaction resulting from drugs (such as amphetamines renal arteries, encasing the inferior vena cava and and methysergide), haemorrhage, surgery, infection aorta (4). Up to 15% have extra retroperitoneal foci and abdominal aortic aneurysm. Approximately 8-10% (5). It characteristically causes medial deviation of of cases are due to a desmoplastic reaction caused by the middle third of the ureter and rarely invades malignant infiltration of the retroperitoneum from the ureteric wall, but if it does the mucosa is in most primary tumours of the breast, lung, stomach, colon, cases spared. Hydronephrosis is due to the absence May 2008 EAST A FRICAN M E DICAL JOURNAL 251 of peristalsis, the ureters being fixed open by the Intravenous urography may show the classic disease process. The duodenum, biliary tract and triad of delayed excretion of contrast material pancreas are rarely involved (1). with unilateral (20%) or bilateral hydronephrosis, Histological examination usually demonstrates medial deviation of the middle third of the ureter fibrous overgrowth with accompanying and tapered narrowing of the ureters at L4/5 level inflammatory infiltrate of lymphocytes, plasma (1). Ultrasound may show a relatively echo-poor cells, and neutrophils, suggesting inflammatory retroperitoneal mass and hydronephrosis (6). rather than neoplastic disease. Mass forming Idiopathic IRF, as in our case is Figure 8 very rare. To our knowledge only 18 cases including Coronal CT showing a left perinephric mass ours have been reported (Table 1). When seen it and associated reduced size and enhancement of can be located any where in the retroperitoneum ipsilateral kidney from the diaphragm to the pelvis (4). Figure 8 shows another example identified by the authors in 2002, demonstrating a left perinephric mass that was proven as retroperitoneal fibrosis and improved on tamoxifen. In these cases it is very difficult to distinguish the resultant mass from a retroperitoneal malignancy, especially lymphoma and retroperitoneal sarcoma. The clinical presentation of IRF is non-specific consisting of dull, poorly localized back or flank pain, weight loss, anorexia, nausea or vomiting and malaise. There is significant morbidity due to progressive renal failure resulting from ureteral entrapment (1,4). Table 1 Reported cases tumour forming idiopathic retroperitoneal fibrosis (1, 3, 4 and 5) Year Author Age Gender Location Tumour size 1978 Chi 42 M Lt. kidney 17 x 4 1985 Arai 69 F Pelvis 5 x 5 1988 Stovall 34 F Pelvis 15 x 12 1991 Muurata 36 F Rt. ureter 6 x 4 1996 Touge 54 F Pelvis 4 x 4 1997 Oh 30 M Rt. kidney 19 x 15 1998 Kuwabara 71 M Bilat. kidneys 4 x 4, 3 x 3 1998 Tekeyama 30 F Pelvis 5 x 3 1998 Haciyanli 60 M Pelvis 6 x 4 1999 Koie 59 M Pelvis 3 x 3 1999 Dejaco 46 M Hepatic hilum 2 x 2 2000 Nakase 55 M Lt. kidney 6 x 6 2000 Wong 3 F Rt. ureter 2 x 2 2003 Tsutomu 76 F Rt. adrenal 8 x 7 2003 Buyl 65 M Lt. ureter - 2004 Warakaulle 73 M Retrocrural 4 x 5 2006 Das 18 F Rt. ureter - 2007 Present case 37 M Lt. ureter 14.2 x 5.6 x 3.4 252 EAST A FRICAN M E DICAL JOURNAL May 2008 CT and magnetic resonance imaging (MRI) Steroid therapy is effective for treating early stage are the modalities of choice for imaging RPF. On IRF, as are other drugs such as cyclosporine, cytotoxic CT, retroperitoneal fibrosis appears as plaque- agents and tamoxifen. Ureterolysis or stents can be like, soft tissue lesion of variable thickness that performed for ureteral obstruction (3). envelops the aorta and IVc between the renal hila and sacral promontory, and extends laterally to In conclusion, a focal and unilateral mass entrap the ureters, resulting in variable degrees forming idiopathic retroperitoneal fibrosis is rare, of hydronephrosis. It does not cause anterior however it should be kept in mind as a differential displacement of the aorta and when this occurs, diagnosis of retroperitoneal masses and image lymphoma or other widespread malignancy should guided biopsy must be performed in such cases for be considered (1). The plaque is isodense to muscle definite diagnosis. on unenhanced CT. 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On T2weighted image, there is high Retroperitoneal fibrosis mimicking retrocrural signal intensity due to high cellularity and fluid lymphadenopathy. Clin. Radiol. 2004; 59: 2923. content in the early active phase, while in the late (CrossRefl/Medline). fibrous phase signal intensity is low due to increased 4. Takashima, T., Onoda, N., Ishikawa, T., et al.